钙钛矿结构弛豫型铁电体的介电弛豫谱研究

Dielectric Relaxation of Complex Perovskite Relaxor Ferroelectrics

通过分析钙钛矿结构弛豫铁电陶瓷铌镁酸铅的复介电响应 ,探讨了其在弥散相变温区的弛豫特征及极性微区、铁电微畴的极化机制。数值拟合表明幂指数 Arrhenius关系比 Vogel- Fulcher关系可更为合理地表征弛豫型铁电体。给出铁电微畴的弛豫响应时间分布函数 。

The dielectric response of complex perovskite Pb(Mg_ 1/3Nb_ 2/3)O_3 with respect to temperature and frequency was measured and discussed around the temperature of dielectric permittivity maximum (T_m). There is no structural phase transition near this temperature. Otherwise, the relaxation behavior is closely like the polar dipole medium. The functional relationship about frequency and temperature of dielectric permittivity maximum was also analyzed to discuss the physical meaning of Vogel-Fulcher relation and of a generalized Arrhenius relation. It is suggested that the new super-exponential Arrhenius relation is better for characterizing the relaxation behavior than the Vogel-Fulcher relation. Based on the polarization theory of dipoles, we substituted an ideal distribution function of relaxation time for microdomains into Schweidler equation, and got a simulation spectrum of dielectric response for relaxor ferroelectrics, which agrees well with experiment results.